xref: /openbmc/linux/arch/riscv/include/asm/ftrace.h (revision 2359ccdd)
1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* Copyright (C) 2017 Andes Technology Corporation */
3 
4 /*
5  * The graph frame test is not possible if CONFIG_FRAME_POINTER is not enabled.
6  * Check arch/riscv/kernel/mcount.S for detail.
7  */
8 #if defined(CONFIG_FUNCTION_GRAPH_TRACER) && defined(CONFIG_FRAME_POINTER)
9 #define HAVE_FUNCTION_GRAPH_FP_TEST
10 #endif
11 #define HAVE_FUNCTION_GRAPH_RET_ADDR_PTR
12 
13 #define ARCH_SUPPORTS_FTRACE_OPS 1
14 #ifndef __ASSEMBLY__
15 void _mcount(void);
16 static inline unsigned long ftrace_call_adjust(unsigned long addr)
17 {
18 	return addr;
19 }
20 
21 struct dyn_arch_ftrace {
22 };
23 #endif
24 
25 #ifdef CONFIG_DYNAMIC_FTRACE
26 /*
27  * A general call in RISC-V is a pair of insts:
28  * 1) auipc: setting high-20 pc-related bits to ra register
29  * 2) jalr: setting low-12 offset to ra, jump to ra, and set ra to
30  *          return address (original pc + 4)
31  *
32  * Dynamic ftrace generates probes to call sites, so we must deal with
33  * both auipc and jalr at the same time.
34  */
35 
36 #define MCOUNT_ADDR		((unsigned long)_mcount)
37 #define JALR_SIGN_MASK		(0x00000800)
38 #define JALR_OFFSET_MASK	(0x00000fff)
39 #define AUIPC_OFFSET_MASK	(0xfffff000)
40 #define AUIPC_PAD		(0x00001000)
41 #define JALR_SHIFT		20
42 #define JALR_BASIC		(0x000080e7)
43 #define AUIPC_BASIC		(0x00000097)
44 #define NOP4			(0x00000013)
45 
46 #define make_call(caller, callee, call)					\
47 do {									\
48 	call[0] = to_auipc_insn((unsigned int)((unsigned long)callee -	\
49 				(unsigned long)caller));		\
50 	call[1] = to_jalr_insn((unsigned int)((unsigned long)callee -	\
51 			       (unsigned long)caller));			\
52 } while (0)
53 
54 #define to_jalr_insn(offset)						\
55 	(((offset & JALR_OFFSET_MASK) << JALR_SHIFT) | JALR_BASIC)
56 
57 #define to_auipc_insn(offset)						\
58 	((offset & JALR_SIGN_MASK) ?					\
59 	(((offset & AUIPC_OFFSET_MASK) + AUIPC_PAD) | AUIPC_BASIC) :	\
60 	((offset & AUIPC_OFFSET_MASK) | AUIPC_BASIC))
61 
62 /*
63  * Let auipc+jalr be the basic *mcount unit*, so we make it 8 bytes here.
64  */
65 #define MCOUNT_INSN_SIZE 8
66 #endif
67